Murray took the first set on a tie-break and at 4-2 up in the second, wasted a golden chance of a second break when he put a routine volley into the net at 30-40.
It mattered little though, with the three-time Grand Slam winner holding his next service game and then breaking the Italian again to prevail 7-6(4) 6-3.
And in his post-match interview, the British icon was bullish when asked what at what ‘percentage’ he was currently operating at in comparison to his prime.
“I think I still have a lot to offer. I don’t know what it is in terms of percentage but I’m still able to compete and win matches against guys who are in the top 10 in the world and I’ve been competitive against guys who were 3 or 4 in the world,” he said.
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“So if my body stays good, and I’m able to build momentum for tournaments and matches, I believe I can get right up there again.”
The former world No 1, who has been working with coach Esteban Carril on a trial basis, also refused to put a timescale on the remainder of his career, but stressed the important of making the most of every opportunity.
“Ideally you want to have a longer term view on things, it’s a bit better in terms of how you improve and how you view results, but I’m also aware that another injury could mean the end,” he added.
“So I want to try and make the most of every single week and be as competitive as I can whilst I’m still able. Every week is important to me right now.”
Murray labelled his victory over Sinner, 20, as his “best win this season” and said the key to moving back up the rankings would be beating the world’s best on a more regular basis.
His immediate focus though will be to further progress in Sweden, but accepted he will have his work cut out against world No 53 Paul, after he beat fellow American Taylor Fritz 6-4 6-4 in his second round match.
“It’s good to turn those matches around and now I’m in the quarters and I want to have a deep run here.
“He’s (Paul) played really well in the second half of the year and had a very good win today against Taylor Fritz.